钢/聚丙烯混杂纤维对HPC深梁受弯性能的影响

为研究钢纤维和聚丙烯纤维对高性能混凝土(HPC)深梁受弯性能的影响,对17根含有不同钢纤维(体积掺量≤1%)和聚丙烯纤维(体积掺量≤0.2%)以及不同纵筋配筋率的HPC简支深梁进行4点受弯性能试验.结果显示:单一纤维或混杂纤维增强HPC深梁的初裂荷载提高了10%～40%;混杂纤维增强HPC适筋深梁的纵筋屈服荷载提高50%～150%,极限受弯承载力提高1～2倍,但无筋的混杂纤维HPC深梁承载力很小,破坏为剪切脆性破坏.试验结果表明:混杂纤维可以极大提高HPC深梁的受弯承载力,但混杂纤维的作用不能代替纵向钢筋的作用;可采用复合材料强度叠加原理及剩余弯曲强度理论来探讨混杂纤维增强HPC深梁的极限受弯承载力计算公式.

Effect of hybrid fibers on bending capacity of high-performance concrete deep beams

In order to investigate the effect of steel fibers and polypropylene fibers on flexural behavior of HPC deep beams,four-point bending tests were conducted on 17 simply supported HPC deep beams with different fiber contents and steel bars.Results show that the first crack load of FRHPC beams (either single type or hybrid) is increased by 10%-40%,the yield load of hybrid FRHPC beams is increased by 50%-150%,and its ultimate flexural capacity is increased by 1-2 times.Thus hybrid fibers can be used to greatly increase the flexural capacity of HPC deep beams,but the failure pattern of hybrid FRHPC beams without steel bar is brittle failure,it means that hybrid fibers can not replace steel bars.The method to calculate the ultimate flexural capacity of hybrid FRHPC deep beams is discussed as well.